Does polyester film have good barrier properties?
Publish Time: 2025-06-11
Polyester film is a high-performance film material made of polyethylene terephthalate by extruding thick sheets and then biaxially stretching. Due to its excellent comprehensive performance, it is widely used in many fields such as electrical insulation, electronic devices, food packaging, medical packaging, magnetic containers, etc. Among them, barrier properties are one of the important indicators for evaluating its application value.1. Gas barrier properties: the key to ensuring the quality of contentsPolyester film has good gas barrier properties, especially for common gases such as oxygen and carbon dioxide. This feature makes it an ideal substrate choice for food and drug packaging. For example, in carbonated beverage bottles, juice packaging bags or vacuum food packaging, PET film can effectively prevent external oxygen from penetrating, avoid oxidation and deterioration of the contents, and thus extend the shelf life of the product. Although PET's barrier properties are slightly inferior to high-barrier materials such as nylon (PA) or ethylene-vinyl alcohol copolymer (EVOH), it has lower costs and better processability, so it still occupies an important position in the field of mid-to-high-end packaging.2. Water vapor barrier: ideal material for moisture-proof protectionIn addition to gas barrier properties, polyester film also has a good barrier effect on water vapor. This is mainly due to its dense molecular structure and moderate polarity, which makes it difficult for moisture to penetrate. In environments with high humidity, such as the rainy season in the south or tropical areas, many products (such as electronic products, medicines, and dry foods) are prone to failure or deterioration due to moisture absorption. Using polyester film as a packaging material can effectively isolate external moisture, keep the internal environment dry and stable, and improve the storage safety and stability of the product.3. Fragrance retention ability: a strong guarantee for freshness and flavor maintenancePolyester film also has good "fragrance retention", that is, it can effectively prevent the volatile components of the contents from diffusing outward. This is especially important for products that are sensitive to odors, such as flavors, condiments, coffee, and tea. For example, in high-end coffee packaging, the use of PET composite film can not only prevent oxygen from entering, but also lock in the aroma of coffee beans, ensuring that consumers can still feel the rich original flavor after opening. This excellent ability to retain fragrance makes polyester film an important choice for packaging materials in the food and daily chemical industries.4. Chemical resistance and oil resistance: broadening the application boundariesIn addition to the basic gas and moisture barrier functions, polyester film also has good chemical resistance and oil resistance. This means that it is not easily corroded or dissolved when it comes into contact with oily substances (such as cooking oil, butter) or certain weak acid and weak alkali solutions, maintaining the integrity of the material structure. This feature makes it widely used in food oil packaging, industrial lubricant packaging and other fields. At the same time, this also enhances the adaptability of PET film in composite packaging structures, and can be combined with other functional materials (such as aluminum foil, PE layer) to construct a multi-layer composite barrier system to achieve a higher level of protection.5. Application in composite packaging: play a synergistic effectAlthough polyester film used alone may be slightly insufficient in high barrier demand scenarios, it is very suitable as one of the structural layers of composite packaging. By compounding with high barrier materials such as aluminized film, PVDC coating, EVOH, aluminum foil, etc., the barrier performance of the overall packaging can be significantly improved.In summary, although polyester film is not the material with the strongest barrier performance on the market, its good barrier performance in terms of gas, water vapor and fragrance makes it one of the preferred substrates in many packaging and industrial application fields. With excellent mechanical properties, temperature resistance, chemical resistance and good processing adaptability, PET film can not only meet the needs of most mid-to-high-end packaging, but also achieve a higher level of barrier effect through composite technology.
